1. Field of Endeavor
The present invention relates to cameras and more particularly to a pin mount for a cryogenically cooled detector.
2. State of Technology
U.S. Pat. No. 7,609,381 to David Wheeler Warren issued Oct. 27, 2009 for a compact, high-throughput spectrometer apparatus for hyperspectral remote sensing provides the state of technology information below.
Hyperspectral imaging is an extremely powerful and broadly applied technique of optical remote sensing. It consists of imaging an object or scene in a multitude of contiguous wavelength intervals. As distinct from multi-spectral imaging, where the wavelength intervals are typically defined by a relatively small number (e.g., <12) of discrete optical bandpass filters, hyperspectral imaging employs a larger number of finer spectral intervals in order to more reliably detect and discriminate between the unique spectral characteristics of natural and artificial materials.
As a tool of remote sensing, for example in geology or astronomy, hyperspectral imaging is generally practical only in wavelength regions where the earth's atmosphere is transparent over ranges of many kilometers and not affected by absorption from atmospheric constituents such as carbon dioxide and water vapor. These regions include the visible and near-infrared (VNIR: 0.4-1.0 μm), short-wave infrared (SWIR: 1.0-2.5 μm), mid-wave infrared (MWIR: 3.0-5.0 μm), and long-wave infrared (LWIR: 8.0-14.0 μm). Depending on the mission and phenomenology of interest, it is common to divide one of these broad spectral regions into 10s or 100s of sampled spectral sub-intervals. Typical numbers range from 32 to 512. These modest spectral resolutions are most practically achieved with spectrometers based on dispersive prism or diffraction grating elements.
In addition to large numerical aperture, spectrometers for hyperspectral remote sensing must have good image quality relative to the size of the detector element. For reliable processing and interpretation of the hyperspectral data, they should also have low image distortions such that the length of the slit image should not change with wavelength (keystone) and the dispersed position of the slit image for a given wavelength should not change with position along the slit (smile). These distortions should be controlled to a small fraction (e.g., < 1/10) of a pixel dimension.
Finally, spectrometers intended for aircraft or satellite use, where volume and mass are often highly constrained, must be as compact as possible. This is particularly true of instruments operating at infrared wavelengths, where the entire instrument is cooled to cryogenic temperatures and demands on cooling resources increase dramatically with instrument volume.
U.S. Pat. No. 7,808,635 to Michael P. Chrisp issued Oct. 5, 2010 for a wide swath imaging spectrometer utilizing a multi-modular design provides the state of technology information below.
These compact arrangements of the imaging spectrometers modules use smaller cryogenic coolers, in the case of infrared systems, facilitating their use in small, medium, and large manned and unmanned aerial vehicles for remote gas detection and detection of solids with characteristic spectral features in the longwave or midwave infrared regimes. These instruments have application for Homeland Defense to check for the presence of potential WMD production and/or use activities without entering the contaminated areas. They also have application for space sensors, where the wide-swath width is extremely important because scenes can only be viewed once an orbit. The wider field of view of this design enables larger swath widths for the remote sensing of larger areas with single pass overflights, and additional spectrometer modules can be added until the field of view of the telescope is completely utilized.